Nitric oxide (NO) and reactive oxygen species (ROS) are important signaling molecules in plant immunity. However, roles of NO and ROS in disease resistance to necrotrophic pathogens are not fully understood. We have recently demonstrated that NO plays a pivotal role in basal defense against Botrytis cinerea and the expression of the salicylic acid (SA) -responsive gene PR-1in Nicotiana benthamiana. By contrast, ROS function negatively in resistance or positively in expansion of disease lesions during B. cinerea-N. benthamiana interaction. Here, analysis in NahG-transgenic N. benthamiana showed that SA signaling is not involved in resistance to B. cinerea in N. benthamiana. We discuss how NO and ROS participate in disease resistance to necrotrophic pathogens on the basis of recent reports.
Keywords: MAPK; NO burst; necrotrophic pathogen; oxidative burst; plant immunity; salicylic acid.